...those agreements were posed to us as advice for our situation, so some of it are their agreements, and some of them are suggestions directed towards our situation - a combo of wisdom/advice/suggestions and ideas from some long time seasons poly peeps.

Well, it is good to have some insight into their experiences -- but don't think that just because your sister knows you, that she also knows what would work for you and your relationships with your husband and any additional partners. There's the possibility that none of your sister's rules would feel reasonable, relatable, or make sense to the unique dynamic that would develop between you, Elemental, and whomever your partner(s) would be.

Thought you and others might find the following excerpt interesting. It's from a short article called "There's No Such Thing As Polyamory," written by Barry Smiler (Electronic Journal of Human Sexuality, Volume 14, April 7, 2011):

"... the poly way is to make up one's own rules, internal to the specific relationship in question, to create a new way of structuring deep aspects of one's life...

This is relevant because it is far easier to buy in to a new set of external rules than to take full responsibility for the self-examination and honest discussion necessary to create your own... The poly ideal is that all interested parties sit down and co-create the rules they want to live by, personally and between themselves. This is worthwhile, but it's not easy, and most people are unwilling to do the tough self-examination and open-hearted negotiation it demands.

Even more, most people are unwilling to take the necessary personal responsibility for creating a successful outcome. With some other paradigms, people accept external rules as provided. This lets them blame any failures on the external rules. But polyamory is where you write your own rules, so "the buck stops here", because "here" is where the framework got set up in the first place.

... polys are simply people who have come to the conclusion that they themselves are the best source for the rules of how they will live. This self-determination appears in many areas of life, and people who feel this right to self-determination in other areas of their lives will decide their own rules for those areas. But when they apply this to decide relationship rules, and give themselves the right to consider a range of nonstandard possibilities, sometimes that is labeled polyamory.

Of course, other times it is labeled other things. And there's self-determination again, because when people aren't feeling constrained to a set of external rules, the rules they choose are unlikely to totally match the rules other people choose, making externally applied labels difficult. Which, I think, explains the common observation that there are as many ways to do polyamory as there are people doing it. People who make up their own rules will seldom reinvent exactly the same rules.

All this is why I offer the reframing that there's no such thing as polyamory. Instead, I suggest that polyamory might well be presented as simply a special case of the larger social ideal of self-determination, a trend that has for hundreds of years been irresistibly moving our society towards individual empowerment and away from cultural/societal strictures, towards everyone's right to manage their own lives in their own way. "